EU Chief Juncker Urges Britons Not To Abandon Decades Of Mutual Gains

European Commission President Jean-Claude Juncker has warned Britain that voting to leave the European Union would be "an act of self-harm" that would endanger decades of mutual gains.

Juncker made his impassioned appeal to British voters two days before they decide in a referendum whether to remain in the EU or exit on June 23.

"To turn your backs on your neighbors and retreat into isolation would go against everything that Europe and the U.K. stand for," Juncker told a business gathering in Athens on June 21. "To leave would be an act of self-harm."

"All too often we take for granted what we have built," Juncker said, listing peace, freedom, prosperity, and a "way of life that is the envy of the entire world" among the EU's achievements.

"This is the patient work of generations of women and men, and we could not have done it without the British people," he said.

"Leaving the European Union would put all this at risk. It would damage what we have achieved so far. And it would diminish what we can achieve tomorrow."

WATCH: Political leaders have been making one last effort to persuade voters ahead of the United Kingdom's referendum on staying in or leaving the European Union. In the western city of Bristol, Prime Minister David Cameron said the country's security was enhanced by EU membership, while Leave campaigner Boris Johnson visited London's Billingsgate fish market. (Reuters)